dibenzyl (2R)-2-{[(2S)-2-({2-[2-(1,1,3-trioxo-1,3-dihydro-2H-1,2-benzisothiazol-2-yl)ethoxy]acetyl}amino)propanoyl]amino}pentanedioate
benzyl (4R)-5-amino-5-oxo-4-{[(2S)-2-({2-[2-(1,1,3-trioxo-1,3-dihydro-2H-1,2-benzisothiazol-2-yl)ethoxy]acetyl}amino)propanoyl]amino}pentanoate